Glen Van Der Kraak

University of Guelph | UOGuelph · Department of Integrative Biology

Temperature and food availability are key drivers of growth and reproductive development in fishes, but information on how they interact is poorly understood. This study investigates the effects of water temperature and food availability on growth, sex ratio and gonadal development of the convict cichlid (Amatitlania nigrofasciata) which is an orna...

Previous studies have implicated the nuclear progesterone receptor (Pgr or nPR) as being critical to ovulation in fishes. This study investigated the expression of Pgr in zebrafish ovarian follicles throughout development as well as putative downstream targets of Pgr by searching the promoter regions of selected genes for specific DNA sequences to...

This study examined the effects of thyroxine (T4) on hematological indices, immune parameters and the stress markers of female sterlet sturgeon. Adult broodstock (708 ± 37 g) were assigned to three groups each consisting of ten females. Fish were injected with coconut oil (control), 1 mg T4 kg body weight⁻¹ in coconut oil (T1) or 10 mg T4 kg body w...

Since the 1940s, effluent toxicity testing has been used to assess potential ecological impacts of effluents and help determine necessary treatment options for environmental protection prior to release. Strategic combinations of toxicity tests, analytical tools, and biological monitoring have been developed. Because the number of vertebrates utiliz...

Physiologically, oxidative stress is considered a homeostatic imbalance between reactive oxygen species production and absorption. From an ecological perspective, oxidative stress may serve as an important constraint to life history traits such as lifespan, reproduction, and the immune system, and is gaining interest as a potential mechanism underl...

There is debate over whether the requirements of GLP are appropriate standards for evaluating the quality of toxicological data used to formulate regulations. A group promoting the importance of non-monotonic dose responses for endocrine disruptors contend that scoring systems giving primacy to GLP are biased against non-GLP studies from the litera...

Extraction of petrochemicals from the surface mining of oil sand deposits results in generation of large volumes of oil sands process-affected water (OSPW). Naphthenic acids (NA) are generally considered to be among the most toxic components of OSPW. Previous studies have shown that NAs are toxic to aquatic organisms, however knowledge of their eff...

To investigate impacts of proposed oil sands aquatic reclamation techniques on benthic fish, white sucker (Catostomus commersonii Lacépède, 1803) were stocked in two experimental ponds, Demonstration Pond containing aged fine tailings capped with fresh water, consistent with proposed end-pit lake designs, and South Bison Pond containing aged unextr...

Abstract A quantitative weight of evidence (WoE) approach was developed to evaluate studies used for regulatory purposes, as well as those in the open literature, that report the effects of the herbicide atrazine on fish, amphibians, and reptiles. The methodology for WoE analysis incorporated a detailed assessment of the relevance of the responses...

Early in 2013, the World Health Organization (WHO) released a 2012 update to the 2002 State of the Science of Endocrine Disrupting Chemicals. Several significant concerns have been identified that raise questions about conclusions reached in this report regarding endocrine disruption. First, the report is not a state-of-the-science review and does...

Herbicides are used to control weeds and are usually targeted to processes and target sites that are specific to plants. As a result, most herbicides are not acutely toxic to fish. Exceptions to this general rule are uncouplers of oxidative phosphorylation and some herbicides that interfere with cell division. Chronic and sublethal effects have bee...

Abstract Conventional risk assessments for crop protection chemicals compare the potential for causing toxicity (hazard identification) to anticipated exposure. New regulatory approaches have been proposed that would exclude exposure assessment and just focus on hazard identification based on endocrine disruption. This review comprises a critical a...

In 1996, the U.S. Congress passed the Food Quality Protection Act and amended the Safe Drinking Water Act (SDWA) requiring the U.S. Environmental Protection Agency (EPA) to implement a screening program to investigate the potential of pesticide chemicals and drinking water contaminants to adversely affect endocrine pathways. Consequently, the EPA l...

Building on breakthroughs recently made at kraft mills, a survey of mechanical pulp and paper mill effluents was undertaken to gain insights concerning potential effects on fish reproduction. Effluents from seven Canadian mills were characterized chemically for conventional parameters such as biochemical oxygen demand (BOD) and total suspended soli...

Male smallmouth bass (Micropterus dolomieu) provide sole parental care including frequent aggressive actions towards conspecifics and potential brood predators. Failure to defend the brood through continual vigilance results in predation reducing the number of offspring and promoting abandonment by the nesting male. However, little is known about h...

The analogs [D-Ala6, Pro9NEt]-luteinizing hormone-releasing hormone (LHRH-A) and [D-Arg6, Pro9NEt]-salmon gonadotropin-releasing hormone (sGnRH-A) were tested in the presence or absence of pimozide (PIM) or domperidone (DOM) for their ability to stimulate an increase in serum gonadotropin (GtH) levels and ovulation in preovulatory female loach. In...

Knowledge of the reproductive biology of wild sturgeon populations is critical to ensure the survival of this unique group of animals. We combined gill-netting surveys, nonlethal blood sampling, radiotelemetry, and egg collection to examine the reproductive biology of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) at a suspected spawning gro...

In this commentary, we critique a recently finalized document titled "State of the Art Assessment of Endocrine Disrupters" (SOA Assessment). The SOA Assessment was commissioned by the European Union Directorate-General for the Environment to provide a basis for developing scientific criteria for identifying endocrine disruptors and reviewing and po...

The objective of this study was to examine the effect of cortisol implantations on gonadal development, sex steroid levels, and ovarian cortisol content in cultured great sturgeon Huso huso. Three groups of 5 fish for each treatment were considered. The experimental groups included: control (capsules containing cocoa butter alone), low cortisol (C(...

Background: Over the past 10–15 years, a substantial amount of work has been done by the scientific, regulatory, and business communities to elucidate the effects and risks of pharmaceuticals and personal care products (PPCPs) in the environment. Objective: This review was undertaken to identify key outstanding issues regarding the effects of PPCPs...

Using a long-term study population of wild smallmouth bass Micropterus dolomieu in a connected river-lake system, we investigated whether circulating glucocorticoid (cortisol) and androgen (testosterone) concentrations are influenced by reproductive investment and nesting environment in fish providing nest-guarding paternal care. For all individual...

Previous studies have demonstrated that oil sands process-affected water (OSPW) impairs the reproduction of fish and that naphthenic acids (NAs), a natural constituent of oil sands, are suspected of being responsible. This study evaluates the potential impact of NAs on the reproduction of adult fathead minnows (Pimephales promelas) under laboratory...

In similar experiments conducted in 1996 and 2009, yellow perch (Perca flavescens) were stocked into two experimental systems: a demonstration lake where oil sands fine tailings were capped with natural water and a lake in a watershed containing bitumen-bearing sodic clays. In both experiments, yellow perch were captured in May from a nearby reserv...

This study investigated two related aspects of male-female reproductive interactions in the family Cyprinidae: (1) whether ovulating female rudd Scardinius erythrophthalmus (subfamily Leuciscinae) induce endocrine and gonadal priming responses in conspecific males, a phenomenon which has been described only in species from the subfamily Cyprininae...

This chapter focuses specifically on the interactions between the hypothalamic–pituitary–interrenal (HPI) stress axis and the hypothalamic–pituitary–gonadal (HPG) reproductive axis and the consequences of these interactions for reproductive processes. It also examines that how stressors and the mediators of the stress response affect the key effect...

Natural environmental periodicity that occurs on both the small scale like day length, or larger scale like lunar light can provide animals with valuable information about resource availability and predation risk. Such environmental cycles are often linked to the timing of reproduction. Here, using the circulating androgen concentrations, gonadal i...

A long-term monitoring study was conducted on effluents from a bleached kraft pulp and paper mill located in Eastern Canada. The study was designed to gain insights into temporal effluent variability with respect to fish reproduction as it related to production upsets, mill restarts and conditions affecting biological treatment performance. Final e...

Pulp and paper mill effluents have been linked to effects on fish reproduction for more than 25 years. To date, the causes of these effects and remedial strategies have eluded investigators. Recent work has shown that the degree of reproductive effect caused by a mill effluent is related to the overall organic content. If verified, this could lead...

The growth promoting ability of bovine growth hormone purified from natural sources (bGH) and genetically engineered rainbow trout growth hormone (rtGH) were compared in rainbow trout (Oncorhynchus mykiss) reared at 17.0 °C. Fish were fed high (on-demand feeding) and low (2.8–4.6% of body weight/d) rations. On both rations, length specific growth r...

The work of Peyton and Thomas in this issue contributes valuable insight into the complex interactions of Gper and Egf in maintaining of the meiotic arrest in zebrafish ovarian follicles. "Involvement of Epidermal Growth Factor Receptor Signaling in Estrogen Inhibition of Oocyte Maturation Mediated Through the G Protein-Coupled Estrogen Receptor (G...

Plasma levels of 3,5,3′-triiodo-L-thyronine (T3), plasma T3 kinetics, and properties of in vivo T3 binding to saturable hepatocyte nuclear sites were studied in fed immature rainbow trout maintained at 12 °C and then held for up to 14 d at 5, 11–12, or 19 °C. Elevation (19 °C) or depression (5 °C) of plasma T3 occurred during the first 3 h followin...

While social interactions influence vertebrate endocrine regulation, the dynamics of regulation in relation to specific behaviors have not been clearly elucidated. In the current study, we investigated whether androgens (testosterone) or glucocorticoids (cortisol) play a functional role in aggressive offspring defense behavior in wild smallmouth ba...

We investigated whether circulating glucocorticoids and androgens are correlated with reproductive investment in smallmouth bass (Micropterus dolomieu), a teleost fish with sole paternal care. Circulat- ing cortisol and androgens prior to and 25 min following a standardized 3 min emersion stressor were quantified for non-reproductive and parental f...

Acknowledgements Clelland, E., and Peng, C. (2009). Endocrine/paracrine control of zebrafish ovarian development. Mol. Cell. Endocrinol 312, 42-52. Fabra, M., Raldua, D., Bozzo, M. G., Deen, P. M. T., Lubzens, E., and Cerda, J. (2006). Yolk proteolysis and aquaporin-1o play essential roles to regulate oocyte hydration during meiosis resumption. De...

The insulin-like growth factor system has garnered recent attention for its potential role in ovarian development in fish with the discovery of the gonad specific IGF-III. It has been shown that recombinant human IGF-I and -II, as well as recombinant zebrafish IGF-III are potent stimulators of oocyte maturation in zebrafish. Previous studies from o...

This study investigated the changes of conventional parameters and selected microcontaminants (MCs) in effluents from three activated sludge (AS) systems including conventional AS (CAS), nitrifying AS (CAS-N) and biological nutrient removal (CAS-BNR) processes at pilot scale. The effluents were also characterized with a suite of biological assays a...

The dynamic relationships between the changes in cortisol synthesis during and after a stressor and the expression pattern of the key genes that regulate the different levels of the hypothalamic-pituitary-interrenal (HPI) stress axis are poorly understood. This study established a novel vortex stressor and characterized its impact at all levels of...

Sexually dimorphic stress responses are present in species across all vertebrate taxa and it has been suggested that these effects are mediated by circulating sex steroids. While a few species of fish have been identified as having a sexually dimorphic stress response, there is conflicting evidence as to the effects of sex steroids on the stress ax...

Large volumes of fluid tailings are generated during the extraction of bitumen from oil sands. As part of their reclamation plan, oil sands operators in Alberta propose to transfer these fluid tailings to end pit lakes and, over time, these are expected to develop lake habitats with productive capabilities comparable to natural lakes in the region....

This study was conducted to determine the potential effects of atrazine exposure on survival and physiological performance in Atlantic salmon (Salmo salar) during the period of smoltification. This study involved two separate experiments in which juvenile Atlantic salmon were exposed to atrazine for a four day period in freshwater after which the f...

Proximate mediators of reproductive behaviors in vertebrates have a long history of study. In fishes, relatively few studies have focused on hormonal control of parental care, despite a comprehensive background on the general physiology of fishes, and the frequent occurrence of parental care behaviors. Studies on this taxon have repeatedly found th...

Locally produced peptide hormones play an important role in the paracrine/autocrine regulation of ovarian development. The insulin-like growth factor (IGF) system is one family of local factors that has not been well studied in the ovary of fish. This study characterized the zebrafish (Danio rerio) ovarian IGF system, its spatial and temporal expre...

The presence of an ovarian IGF system in teleosts suggests a distinct role in reproductive physiology. This study investigates the role of the ovarian IGF system in oocyte maturation, the acquisition of maturational competence and steroidogenesis in the zebrafish (Danio rerio). Recombinant human IGF-I and IGF-II stimulated germinal vesicle breakdow...

The serotonin re-uptake inhibitor fluoxetine was selected for an environmental risk assessment, using the most recent European guideline (EMEA 2006) within the European Union (EU)-funded Environmental Risk Assessment of Pharmaceuticals (ERAPharm) project due to its environmental persistence, acute toxicity to nontarget organisms, and unique pharmac...

We evaluated plasma testosterone (T) and 17beta-estradiol (E2) levels and ovarian aromatase CYP19a gene expression following a single intraperitoneal injection of Chilean pulp and paper mill effluent extracts into juvenile triploid rainbow trout. Fish injected with untreated effluent extracts had increased plasma T after 4 days, while plasma E2 con...

Relatively little is known about the physiological response and mortality consequences of the return of anadromous fish to freshwater (FW). We explored the consequences of the return to FW by collecting maturing sockeye salmon from the marine waters off the mouth of the Fraser River and holding approximately 50 sockeye in each of five treatments: s...

Recently, a segment of the Adams-Shuswap sockeye salmon (Oncorhynchus nerka) population initiated freshwater migration several weeks earlier than historically recorded, resulting in high mortality rates. The comigrating Chilko population maintained their historic river entry timing and did not experience elevated mortality. To test the hypothesis t...

To test the hypothesis that the hypothalmic gonadotropin-releasing hormone (GnRH) and testosterone (T) co-treatment stimulates both the hypothalmo-pituitary-gonadal (HPG) and hypothalmo-pituitary-interrenal axes, the reproductive and osmoregulatory responses of pre-adult pink salmon Oncorhynchus gorbuscha were compared after GnRH and T administrati...

Under the Canadian Environmental Effects Monitoring (EEM) program for pulp and paper effluents, the observation of a national response pattern of decreased gonad size and increased fish condition and liver size has triggered a centralized multiagency investigation of cause (IOC) of reproductive impacts in fishes. The purpose of the component of the...

This study presents evidence that cathepsin B, a lysosomal protease, may be involved in the regulation of apoptosis during serum-starvation in teleost follicles. Zebrafish vitellogenic follicles were isolated, incubated under serum-free conditions and homogenized. The follicle extracts demonstrated caspase-3-like activity using the fluorogenic subs...

This chapter discusses the neuroendocrine pathways that regulate the synthesis and release of the pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), in teleost fish with a primary focus on the multiple forms of both gonadotropinreleasing hormone (GnRH) and its receptors in relation to their actions within the...

This study investigates the regulation of prostaglandin (PG) synthesis in the ovaries of sexually-mature zebrafish (Danio rerio). We examined the ovarian expression of genes within the arachidonic acid (AA) pathway, and the ovarian levels of 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha,20beta-P), 17beta-estradiol (E(2)), and PGF(2alpha) in spa...

Male largemouth bass (Micropterus salmoides) provide sole parental care over a 4-6-wk period to a single brood, fanning the eggs to keep them oxygenated and free of silt and defending the brood until the offspring develop antipredator tactics. During this period, fish are highly active and have few opportunities for feeding, so this activity is ene...

The African clawed frog (Xenopus laevis) has been identified as an appropriate sentinel for testing endocrine activity of existing chemicals in North America and Europe. Some reports suggest that the herbicide, atrazine (CAS Number [1912-24-9]) causes ovarian follicles to form in the testes of this frog. X. laevis collected from North East (NE) sit...

This study explored the impact of nominal concentrations of ethinylestradiol (EE(2); 10ng/L), fluoxetine (FLU; 0.32, 3.2, 32microg/L), and 1-50% treated municipal effluent on reproduction and liver function in sexually mature female zebrafish over a 7-day period. Compared with the control groups, FLU (32microg/L) and 50% effluent treatment signific...

Large volumes of oil sands process-affected waters (OSPW) are produced during the extraction of bitumen from oil sand. There are approximately 10(9) m(3) of OSPW currently being stored in settling basins on oil sands mining sites in Northern Alberta. Developers plan to create artificial lakes with OSPW and it is expected that this water may eventua...

Fractions of methylated naphthenic acids (NAs) isolated from oil sands process-affected waterwere collected utilizing Kugelrohr distillation and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. 1H NMR analysis revealed that the ratio of methyl ester hydrogen atoms to remaining aliphatic hydrogen atoms increased from 0.130 to 0.2...

This study explored the potential for ovarian-derived prostaglandins (PGs) to be involved in the regulation of oocyte maturation and ovulation in zebrafish. It was demonstrated that cultured vitellogenic follicles have the capacity to produce prostaglandin E(2) (PGE(2)) and PGF(2alpha) in response to arachidonic acid (AA) in a concentration-depende...

Recent expansion within the oil sands industry of the Athabasca Basin of Alberta, Canada has led to increased concern regarding process-affected wastewaters produced during bitumen extraction. Naphthenic acids (NAs) have been identified as the primary toxic constituents of oil sands process-affected waters (OSPW) and studies have shown that with ti...

Animal migrations typically occur within a predictable time frame and sequence, but little is known about the triggers that initiate migration, despite their importance in animal ecology and for resource management. The migration of adult sockeye salmon (Oncorhynchus nerka) in the Fraser River, British Columbia, Canada, is an excellent model to stu...

Fish migration represents one of the most complex and intriguing biological phenomena in the animal kingdom. How do fish migrate such vast distances? What are the costs and benefits of migration? Some of these fundamental questions have been addressed through the use of telemetry. However, telemetry alone has not and will not yield a complete under...

Athabasca oil sands mining in northern Alberta produces process-affected waters that are characterized by the presence of naphthenic acids, polycyclic aromatic hydrocarbons, and high salinity. The purpose of this study was to examine the impact of these process-affected waters on reproductive and stress related endpoints in mature goldfish, Carassi...

Polygyny is regarded as a beneficial strategy for males, whereas females mated with polygynous males (males simultaneously paired to more than one female) often suffer a reduction in pair male contributions. This study examined the costs and benefits associated with polygyny in the cooperatively breeding cichlid Neolamprologus pulcher. In this spec...

For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size,...

Little research has examined individual variation in migration speeds of Pacific salmon (Oncorhynchus spp.) in natural river systems or attempted to link migratory behavior with physiological and energetic status on a large spatial scale in the wild. As a model, we used three stocks of summer-run sockeye salmon (Oncorhynchus nerka) from the Fraser...

This study examines whether retinoids are essential in the reproduction of zebrafish. Using RT-PCR, it was shown that the ovaries and testes express enzymes that synthesize and metabolize the hormone retinoic acid (RA) (raldh2 and cyp26a, respectively), and RA receptors (raraa, rarga, rxrba, rxrbb, rxrga but not rxrab). Three new isoforms of rxrba...

Reproductive success and development of F2 offspring from F1 adult African clawed frogs (Xenopus laevis) exposed to atrazine throughout larval development and as sexually mature adults was examined. Larval X. laevis were exposed to one of four nominal concentrations of atrazine (0, 1, 10, 25 microg atrazine/l) beginning 96 hr after fertilization an...

For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size,...

Among taxonomically widespread cooperatively breeding vertebrates, those with non-breeding helpers-at-the-nest provide an excellent opportunity to understand the proximate mechanisms underlying care and allocare. In this study, we examined androgen levels in relation to care behavior in a cooperatively breeding cichlid fish, Neolamprologus pulcher,...

Since 1996, some populations of Fraser River sockeye salmon (Oncorhynchus nerka Walbaum in Artedi, 1792) have begun spawning migrations weeks earlier than normal, and most perish en route as a result. We suspect that a high midsummer river temperature is the principal cause of mortality. We intercepted 100 sockeye during normal migration near a spa...

The herbicide atrazine is widely used in agriculture for the production of corn and other crops. Because of its physical and chemical properties, atrazine is found in small concentrations in surface waters--habitats for some species. A number of reports on the effects of atrazine on aquatic vertebrates, mostly amphibians, have been published, yet t...

The estrogen-dependent process of vitellogenesis is a key function on oviparous fish reproduction and it has been widely used as an indicator of xenoestrogen exposure. The two estrogen receptor (ER) subtypes, ERalpha and ERbeta, are often co-expressed in the liver of fish. The relative contribution of each ER subtype to modulate vitellogenin produc...

Adult sockeye salmon (Oncorhynchus nerka, N=179) from six Fraser River populations (British Columbia) were intercepted in continental shelf waters ∼215km from the Fraser River mouth, gastrically implanted with acoustic transmitters, non-lethally biopsied for blood biochemistry, gill Na+,K+-ATPase activity and somatic energy density and then release...

The aim of the present study was to evaluate, in vivo, the potential of o,p'-DDT to disrupt the endocrine system of mature male tilapia. In particular, the possibility that o,p'-DDT effects were mediated directly via the estrogen receptor (ER). Compounds with known ability to bind to the ER were employed: estradiol to induce and tamoxifen to inhibi...